Telegraph system



July 4, 1933. H, WOOD TELEGRAPH 5 [5 TEM Filed Jan. 14, 1932 INVENTOR HA RR Y WOO D ATTORNE? Patented July ,4, 1935 i stars 7 NEW YORK were earner orsiscs HARRY HOOD, 9F BBGGKLYN, NEVJ YGBK, ASSEGNOR. T TNTE RNATIONAL C(JMMUNI- GATZQIIS LfiBQRATGRIES, ENC.,.0l- NEWARK, NEW JERSEY, A CORPORATION OF TELEGRAPH SYSTEM -App1ieaticn filed January 14, 1932. Serial No. 586,577.

This invention relates generally to apparatus employed for the transmission and reception of electricalimpulses, and more particularly toa method of and means for transmitting impulses by means of automatic telegraph transmitters of the type controlled by a suitably perforated tape.

In the following description, I have applied my invention to the well known Muirhead standard automatic transmitter. lVith very little modification the invention may also be used with the lVheatstone transmitter. These instruments may, of course, be 'moc i lied to be used with either the, Morse cable code or the VVheatstone code. For ease in description the Morse cable code, as used on prepared tape, will be assumed in the following disclosure. The prepared tape, as is customary, has three rows of holes, the upper rowfor the transmissionof dots, the middle rowfor continuously engaging the starwhee'l, and the lower rowfor the transmission of dashes.

The usual reciprocating pins in the normally used lvluirhead transmitter control both thelength of the signal and the polarity of t e impulses transmitted, as well as the earthing of the cable associated with the system. Because of this independent action, it

is very CllfllCUli) to avoid unequal line usage and, consequently, unequal signal duration with respect to the positive andnegative impulses transmitted over the cable. Furthermore, in the usual automatictransmitter circuit, an excessive amount of sparking takes place at the contracts associated therewith and, consequently, the contacts become badly pitted after a short period of use.

i It is an object of this invention to permit of a big margin in pecker adjustment so that several automatic tFEt-11Sl11ll3tfS,82tCl1 with dif- Another object is to diminish the amount of lost time occurring in the operation of the transmitter contacts and, simultaneously, to decrease the lag in the action of the relay armatures, thereby giving a fuller reversal signal.

Other objects and advantages ofthis'invention, as well as means for. attaining these objects, Will be apparent upon reference to the accompanying drawing in connection with the following description. I

Fig. 1 shows a portion of a Muirhead automatic tape transmitter embodying my invention and, also, diagrammatically, the local transmitting or sending-on relays associated with and controlled by the transmitter;

Fig. 2 shows another diagrammatic circuit .ici a eusec inconne ii 'iia wh 1 m b l ctoi wtl n automatic transmitter; and

' Fig. 3 is still another drawing of a circuit embodying my invention when used in conjunction with an automatic transmitter.

in the embodiments illustrated in the drawing, I have shown my invention as em ployed for the automatic operation of transmitting relays. Referring now more particularly to Fig. 1, only such details of the transmitter are shown as are necessary to clearly illustrate the association ofthe transmittiu relays with the contact mechanism of the transmitter. The contact mechanism will be immediately recognized by those familiar with the art. 3

in Fig. 1, numeral 1 is a dot transmitting relay and 2 is a dash transmitting relay. These relays may be normally biased, mechanically or electrically,to spacing position, although in this specific case the same windin'g serves as both a biasing and an operat ing winding. I

Reay windings 3'and i are the operating windings of the dot and dash transmitting relays, respectively.

'7 The transmitter proper is clearly shown only insofar as is necessary for a clear understanding of the wiring diagram.

Peclrer pins, 16, 17 enter the successive perforations of a transmitting tape. The peck- 18 carried by shaft 20. Shaft 20 is driven by the phonic wheel. Bell crank lever 14 carrying pecker pin 16 on one arm has the dash contact 23 secured to its other arm; similarly, dot contact 21 is secured to bell crank lever 15 to which pecker pin 17 is pivoted.

Lever 25 is a means for insuring the closing of the circuit at the proper time and has curbing contact 26 mounted at one end. This lever is also actuated by cam 18. The curbing contacts 26, 27 are included in both the dot and dash circuits so that neither circuit is completed until the curbing contacts are closed. Bell crank levers 14, 15 and 25 are mounted on shaft 21.

The circuit consists essentially of arranging tour resistances for each relay in such a way as to provide potentiometer circuits and, subsequently, shorting-out resistances of this potentiometer, in order to obtain current through the associated relay windings in the proper direction, e. g., for marking or spacing. Thus, for dash relay2 resistances 5, 6, T and S are arranged as shown. For adequate operation these resistances may, for example, be taken as 3000, 2000, 2000 and 1000 ohms, respectively. These values are given as illustrative only and may be modified so as to produce the desired results. For transmitting space signals the dot'and dash contacts 24 and 2 respectively. are open and the curbing or eartliing contacts 26, 27 are closed. This completes a circuit from positive battery through curb contacts '26, 27, line 13, line 80, resistance 5, operating coil 4, resistance 7, to negative battery. The current flows in the spacing direction through relay 2. A somewhat similar circuit may be traced through the potentiometer circuit associated with dot relay 1, also in the spacing direction. The relays. if biased, are thus more firmly held against their respective spacing contacts. For transmitting a dash, pecker 16 entersa perforation in the tape. This closes dash contact 23, thereby completing a circuit, upon the closure of curbing contacts 26, 27 from positive battery through line 31, resistance 8 and resistance 7 in series, this circuit being in parallel connection with a circuit comprising line 13. line 30, resistance 5 and resist ance 6, both circuit-s then going to negative battery. Because of the difference in resistance between 5 and 8, a. difference of potential exists across Winding 1 of dash relay 2, causing a current to flow in the direction from 32 to 33. This causes the tongue of dash relay 2 to go to its marking contact, thereby putting negative or marking battery on the cable. The circuit through the dot relay remains unchanged and, therefore, its tongue remains in spacing position.

In a similar manner, by proper choice of resistances 9, 10, 11 and 12 and by tracing a similar circuit through the dot relay and its associated resistances, the transmission of a dot signal may be readily effected.

As an example of the mode of operation the sequence of operations in transmitting the letter A (dot. dash, space) will be given:

(1) Dot contact closes;

(2) Earthing contact closcs-dot signal begins;

(3) Earthing contact opens;

(4) Dot contact opens, dash contact closes;

(5) Earthing contact closes-dot signal ends, dash signal begins;

(6) Earthing contact opens;

(7) Dash contact opens;

(8) Earthing contact closesdash signal ends, space signal begins;

(9) Earthing contact opens;

(10) Contact for next pulse closes; and

'(11) Ear-thing cam closes-space signal ends.

From the above it can be seen that the beginning and ending of: each signal is determined by the earthing contact, and that all signals are timed from the same source and are independent of the travel time of the pecker rods and contacts.

As the windings of the relays ire always shunted by tworesistances, no inductive circuit is broken by the earthing contact, so that the troubles from sparking are practically eliminated.

In all the figures corresponding numerals indicate similar apparatus.

Figs. 2 and 3 show alternative apparatus for obtaining results similar to the above. In F ig. 2 a mechanical bias is illustrated, whereas in Fig. 3 a biasing coil, which may be shorted-out of circuit, is illustrated. The relays in the circuit shown in F ig. 3 will thus be more sensitive than those shown in Fig. 2. These circuits all disclose arrangen'ientstor obtaining exact equality of all signaling impulses for block signals. I

Fig. 2 is a modification of Fig. 3, and therefore F ig. 3 only will be described in detail.

This circuit (Fig. consists essentially of arranging two resistances for the biasing winding of each relay and one resistance in series with the operating windings of both relays, so as to provide a potentiometer circuit in order to obtain current through the relay windings in the proper direction. Thus, for dot relay 1 and dash relay 2 resistances 46, 47 and 48 are arranged as shown. For adequate operation these resistances may, for example, be taken as 3000, 2000, 2000 and 3000 ohms, respectively. These values are given as illustrative only and may be modified so as to produce the desired results. For transmitting space signals the dot and dash contacts 2& and 2", respectively, are open and the curbing or earthing contacts 26, 27 are closed. This completes a circuit from positive battery through curb contacts 26, 27, line in the winding 13,- then through twopa-rallel circuits comprising a first circuit over line 49, spacing coil 43 of the dot relay, resistance 45, resistance 46, and a second circuit over line 50, spacing coil 44 of the dash relay, resistance 48, resistance 47, both parallel circuits then going to negative battery; I

The circuit is completed with the closing of the cam contacts at 26, 27. During spacing impulses the potential drops from a maXimum at 26, 27 through the spacing winding 43 of dot relay 1, the 3000 ohm resistance 45, the 2000 ohm resistance 46, to zero potential at negative battery. Also, the potential drops from a maximum at 26, 27, through spacing winding 44 ofdash relay 2, the 3000 ohm resistance 48, the 2000 ohm resistance 47, to zero potential at negative battery. The direction of the currents in the spacing coils of both relays is such as to cause the tongues of the respective relays to move to their spacing contacts. Points 52 and 51 are at the same potential and, therefore, no current will flow in the o1 erative windings 3 and 40f the dot and dash relays, respectively. p

For transmitting a dot, pecker 17 enters a perforation in the tape. This closes dot contact 24, thereby completing circuit from sitive battery, upon the 'closing of the curbg Contact, short-circuiting biasing winding43 of dot relay 1 and 3000 ohm resistance 45. The other circuits remain unchanged. Thus, when the curbing contacts 26, 27 then close and complete the circuit, the voltage at point 52 is at the maximum value, while the potential at 51 is below :themaximum because of the potential drop occurring upon its passage through :coil 44' and resistance 48. Thus, the potential atthe point 52 ishigher than at "51 anda current will flow through the main or operative windings and 4 in the direction from 52 to '51. Thisdirectionis such as to have spacing effect in the Wind ing 4 of the dash relay and a inarkinjg'eiiect 3 of the dot relay. No current will flow through the spacing winding 43st the dot relay while the spacingeiiect a5 is further increased by the current flowingin l.

From the above description the action during a .dash impulse will be obvious.

' The circuits are completed only when the curbing contactsare closed and they need to beclosed for only a very short period as-the removal of biasing eifects makes the relays immediately responsive. If we take the length of an impulse. as 360, or one revolution of the cam shaft, then a closure of the curbing contacts for about .60 should be ample. By this adjustment the pecker contacts are closed for a considerable number of degrees before the curbing contacts complete the'circuit; also the pecker contacts remainfclosed for an equal interval after the curbing contacts have broken the circuit.

ends

By this means all the impulses are equal irrespective, to alarge extent, of the actio'n'and adjustments of the transmitter levers and contacts. i

lViththis circuit the time constant of the relays will be quicker than. is the case with the methous previously discussed, because currents are, not simultaneously opposing each other in different windings of the same relay, one in a'spacing direction and the other in a niarking'direction- From the above description the operation of the apparatus in Fig. 2 will be clear and, therefore, no detailed description thereof will be attempted. It will suiiice to say-that Fig. 2shows'a mechanically biased set of relays with no biasing winding. All the other features are similar to those discussed above in connection with F112. 3.

It shouldbe noted that various modifications of the apparatus are possible. With the apparatus shown in Fig. 2 the signals are not one hundred percent block signals, as the bias. acts to ground the cable after the curbing contact has broken. For example, the sequence of operations in transmitting the letter A (dot, dash, space) with the ap? paratus shown in Fig. 2 will be as follows:

(1) Dot contact closes;

(2) Curbing contact closes. begins;

(3) Curbing Contact opensdot signal (4) Dot contact opens, dash contact closes;

ends; and (10) Contact for next signal pulse closes,

etc. I

From the aoparatus, shown in F 1 and 3, one hundred percent block signals are produced.

1. In an automatic telegraph transmitter,

the combination with a pair of contact levers carrying plns respectlvely adapted to pass through the dot and dash perforations of a signal tape, of an auxiliary contact lever, a

line, a pair of relays and potentiometer means associated in a circuit comprising said relays and contact levers, said relays being effective when the auxiliary lever is operated together with one of the pair of levers to put positive battery on said line and when the auxiliary lever is operated together with the other of dot signal 9 These figures are given as illustra- 'tive oi the general method here involved.

the pair of levers to put negative battery on said line, and when the auxiliary lever is operated alone to ground said line.

2. In an automatic telegraph transmitter, the combination with a pair of contact levers carrying pins respectively adapted to pass through the dot and dash perforations of a signal tape, of an auxiliary. contact lever, 21 line, a pair of relays and potentiometer means portions of which continuously shunt the windings of said relays, said potentiometer being associated in a circuit comprising said relays and contact levers, said relays being effective when the auxiliary lever is operated together with one of the pair of levers to put positive battery on said line and when the auxiliary lever is operated together with the other of the pair of levers to put negative battery on said line, and when the auxiliary lever is operated alone to ground said line.

3. In an automatic transmitter, the combination with a pair of contact levers carryin g pins respectively adapted to pass through the dot and dash perforations of a signal tape, of an auxiliary contact lever, a first and a second relay, each having an operating coil, potentiometer means associated in a circuit comprising the contact levers and the operating coils, said coils being de-energized bot-h normally and when said auxiliary lever alone is operated, the operation of the auxiliary lever subsequent to the operation of one of the pairs of levers causing such a drop of potential across the windings of said relays as to make the tongue of the first and second of said relays go to marking and spacing positions respectively and the operation of the other of said pair of levers together with the subsequent operation of the auxiliary lever causing an opposite effect in said relays.

4. In an automatic transmitter, the combination with a pair of contact levers carrying pins respectively adapted to pass through the dot and dash perforations of a signal tape, of an auxiliary contact lever, a first and a second relay, each having a continuously shunted operating coil, potentiometer means associated in a circuit comprising the contact levers and the operating coils, said coils being de-energized both normally and when said auxiliary lever alone is operated, the operation of the auxiliary lever subsequent to the operation of one of the pairs of levers causing such a drop of potential across the windings of said relays as to make the tongue of the first and second of said relays go to marking and spacing positions respectively and the operation of the other of saidpair of levers together with the subsequent operation of the auxiliary lever causing an opposite effect in said relays.

5. In an automatictelegraph transmitter, the combination with a pair of contact levers carrying pins respectively adapted to pass through the dot and dash perforations of a signal tape, of an auxiliary contact lever, a pair of relays each having a biasing coil and an operating coil in circuits adapted to be completed by the contacts of said levers, said coils being normally de-energized, each of said biasing coils being energized when the auxiliary lever alone is operated, one relay having its biasing coil de-energized and its operating coil energized in marking direction, the other relay having its biasing coil and its operating coil energized in spacing direction when the lever pin associated with the first-mentioned relay passes through a perforation in the tape and the auxiliary lever is subsequently operated.

6. In an automatic telegraph transmitter, the combination with a pair of contact levers carrying pins respectively adapted to pass through the dot and dash perforations of a signal tape, of an auxiliary contact lever, a pair of relays each having'a biasing coil and an operating coil both of said coils being continuously shunted and disposed in circuits adapted to be completed by the contacts of said levers, said coils being normally de-energized, each of said biasing coils being energized when the auxiliary lever alone is operated, one relay having its biasing coil deenergized and its operating coil energized in marking direction, the other relay having its biasing coil and its operating coil energized in spacing direction when the lever pin associated with the first-mentioned relay passes through a perforation in the tape and the auxiliary lever is subsequently operated.

7 In an automatic telegraph transmitter, the combination with a pair of contact levers carrying pins respectively adapted to pass through the dot and dash perforations of a signal tape, of an auxiliary contact lever, a pair of relays each having a biasing coil and an operating coil disposed in potentiometer circuits adapted to be completed by the contacts of said levers, said coils being normally tie-energized, each of said biasing coils being energized only when the auxiliary lever alone is operated, one relay having its biasing coil tie-energized and its operating coil energized in marking direction, the other relay having its biasing coil and its operating coil energized in spacing direction when the lever pin associated with the first-mentioned relay passes through a perforation in the tape and the auxiliary lever is subsequently operated.

8. In an automatic telegraph transmitter, the combination with a pair of contact levers carrying pins respectively adapted to pass through the dot and dash perforations of a signal tape, of an auxiliary contact; lever, a pair of relays each having a biasing coil and an operating coil both of said coils being continuously shunted and disposed in potentiometer circuits adapted to be completed by the contacts of said levers, said coils being relay passes through a perforation in the tape and the auxiliary lever is subsequently operated, and the operation of the other of said pair of levers together with the subsequent operation of the auxiliary lever causing an opposite'eflect in said relays.

In witness whereof, I hereunto subscribe my name this 13th day of January 1932.

HARRY WOOD. 

